A car manufacturer sent out survey cards to owners who had purchased new cars. The survey card only had boxes to check for replies, and no places to write additional comments. What is a possible result of the design of the comment cards?
A.
The results cannot be examined because comment cards were used.
B.
The owners who filled out the cards may not express their true opinion.
C.
People would refuse to fill out the cards.
D.
Not enough cards would be returned.